The present invention relates to a color-converting film and a light-emitting apparatus using the same.
Self-emission type, high visible, light-emitting apparatuses usable for a lightweight thin display, etc. have been widely studied and developed in recent years. Particularly, attention has been paid to a light-emitting apparatus comprising an organic light-emitting device, which is advantageous in that its emission spectra can be easily controlled and that it can be driven by a low applying voltage.
Known as the multi-color (full-color) light-emitting apparatus using the organic light-emitting device are: (a) apparatuses where three types of light-emitting layers each acting to emit red, green or blue light are disposed on a substrate to form picture elements of the three colors (Japanese Patent Laid-Open Nos. 57-157487, 58-147989, 3-214593, 8-227276, etc.); (b) apparatuses where three types of color filters each acting to separate white light into red, green or blue light are provided on the light output side surface of a white light-emitting device (Japanese Patent Laid-Open Nos. 1-315988, 2-273496, 3-194895, 7-142169, etc.); (c) apparatuses where color-converting films each acting to convert blue light into red or green light are provided on the light output side surface of a blue light-emitting device to obtain three colors (Japanese Patent Laid-Open Nos. 3-152897, 8-279394, 8-286033, 9-80434, 9-92466, 9-208944, etc.); etc. However, the light-emitting apparatuses of above (a) demand complicated processes for disposing the three types of light-emitting layers on the substrate, to be poor in yield and mass-productivity. The light-emitting apparatuses of above (b) exhibit low light-emitting efficiency because most of light emitted therefrom is absorbed by the color filters, thereby requiring high applying voltage. The light-emitting apparatuses of above (c) also require high applying voltage because the conventional color-converting films are not always excellent in fluorescence conversion efficiency.
White light-emitting apparatuses have been conventionally used for illumination light sources, etc. However, such the conventional white light-emitting apparatuses that are described in publications recited as references for the apparatuses of (b) need a plurality of light-emitting materials, whereby color balance of light emission thereof is often changed over time.
An object of the present invention is to provide a color-converting film excellent in fluorescence conversion efficiency, and a light-emitting apparatus comprising the color-converting film, which can be driven by a low applying voltage with high stability and can be easily produced with high yield.
As a result of intense research in view of the above object, the inventor has found that a color-converting film using an ortho-metallation complex is excellent in the fluorescence conversion efficiency, and that a light-emitting apparatus comprising the color-converting film and an organic light-emitting device can be driven by low applying voltage. The present invention has been accomplished by the findings.
Thus, a color-converting film of the present invention comprises a light-transmittable substrate and a color-converting layer containing an ortho-metallation complex disposed thereon.
The color-converting layer preferably contains a dye and/or a pigment, the dye being preferably selected from the group consisting of stilbene compounds, coumalin compounds, cyanine compounds, pyridine compounds, xanthine compounds, naphthalic imide compounds and oxazine compounds. The dye-content is preferably 0.1 to 20 weight % in the color-converting layer.
The ortho-metallation complex is preferably an iridium complex, a palladium complex or a platinum complex, particularly preferably an iridium complex. The ortho-metallation complex preferably includes at least one ligand selected from the group consisting of 2-phenyl pyridine derivatives, 7,8-benzoquinoline derivatives, 2-(2-thienyl)pyridine derivatives, 2-(1-naphthyl)pyridine derivatives and 2-phenylquinoline derivatives. The content of the ortho-metallation complex is preferably 0.1 to 99 weight % in the color-converting layer.
The color-converting film of the present invention preferably comprises a light-shielding layer. The light-shielding layer is preferably disposed on the upper surface or the lower surface of the light-transmittable substrate.
A light-emitting apparatus of the present invention comprises the above color-converting film, and an organic light-emitting device having a transparent electrode, an organic light-emitting layer and a counter electrode provided on the color-converting film. The light-emitting apparatus of the present invention is usable as a multi-color light-emitting apparatus or a white light-emitting apparatus.